Dissertation > Excellent graduate degree dissertation topics show

Basic Research on the Photocathode and Nano Absorbers in Novel Solar Cells

Author: PengShengJie
Tutor: ChenJun
School: Nankai University
Course: Inorganic Chemistry
Keywords: Nanocrystals Sulfide Dye-sensitized solar cells Thin film solar cells Photocathode
CLC: TM914.4
Type: PhD thesis
Year: 2010
Downloads: 83
Quote: 1
Read: Download Dissertation

Abstract


Solar cells, as a way to replace energy for sustainable development, are developing rapidly in recent years, due to their cleaning, cheapness, and high efficiency. However, solar cells have not been widely used in the long run because of their shortcomings of high fabrication cost and low conversion efficiency. Therefore, reducing the preparation cost and improving the conversion efficiency of solar cells are the key points in the future study. The development of novel low-cost solar cells, which include dye-sensitized solar cells (DSCs) and nanocrystal solar cells, has become a research hotspot.The photocathode of DSCs is usually platinum-based films. However, its high price limits its commercial application. While, in thin film solar cells, CuInS2, as a direct band-gap semiconductor, possesses the advantages of a large absorption coefficient and appropriate band gap to match the solar spectrum. However, the film preparation, which needs high vacuum sophisticated equipment, and the composition and optical properties of CuInS2 are sensitive to the preparation process, both limiting their industrial application.Therefore, based on the summarization of the progress of solar cells, this thesis carried out the basic research on the photocathode in DSCs, and shape-controlled CuInS2 nanocrystals with different sizes by a one-step chemical method and their application in a new type of thin film solar cells fabricated by a simple chemical drop-casting method. In addition, the optical properties of the as-prepared CuInS2 nanocrystals and the photovoltaic properties of the solar cells were investigated. The main content of this thesis is as follows:(1) NiPt films as the photocathode in DSCs were investigated. Films of Ni1-xPtx (x=0,0.02,0.04,0.06,0.08) were deposited on FTO glass substrates by a chemical plating and oxidation-reducation method. The Pt loading in NiPt films could be controlled by the reaction time. The results showed that the Ni0.94Pt0.06 film with a Pt loading of 5.13μm/cm2 exhibited high catalytic performance toward triiodide reduction, high light reflectance, and low charge-transfer resistance, thereby enhanced the conversion efficiency of DSC. The DSC based on the Ni0.94Pt0.06 photocathode showed an overall conversion efficiency of 8.21%, which was higher than that of the DSC with a pure Pt photocathode obtained by conventional thermal decomposition (7.33%). Furthermore, the DSC based on the Ni0.94Pt0.06 photocathode showed good stability. The results showed that the Nio.94Pt0.06 photocathode is potential in the fabrication of DSCs with large scale and low cost.(2) High surface area microporous carbon as the photocathode in DSCs was investigated. High-surface-area microporous carbon, replacing conventional Pt photocathode, was fabricated by cornstalks, and the photovoltaic characterization in DSCs was measured. The photocathode, which contained microporous carbon active material, Vulcan XC-72 carbon black conductive agent, and TiO2 binder photocathode, showed a low charge-transfer resistance of 1.32Ωcm2. The DSCs assembled with the MC film photocathode presented an overall conversion efficiency of 7.36% under AM1.5 (100 mW cm-2), which was comparable to that of the DSCs with Pt photocathode prepared by conventional thermal decomposition. Especially, the open-circuit voltage reached 798 mV, which was increased by 60 mV compared to that of pure Pt photocathode. The use of high surface area carbon as a photocathode played an important role in the reduction of the fabrication cost of DSCs due to the avoiding use of precious metal Pt.(3) CuInS2 nanocrystals with different sizes and their photovoltaic application were investigated. Well-defined and monodisperse CuInS2 with sizes ranging from 2-10 nm were synthesized via a facile one-pot chemical approach using Cu-oleate, In-oleate, sulfur as the reactants in oleic acid and oleylamine media. The effects of oleylamine, which acted as a reductant and the capping agent, on the size and purity of the products were thoroughly investigated. UV-vis absorption and fluorescence spectra measurements showed that the products had the property of quantum confined effect. In addition, other types of pure ternary chalcogenide cmopounds CuIn(SxSe1-x)2(x=0,0.3,0.5,0.7), and AgInS2 nanocrystals with size of about 10 nm were synthesized by using the same method. Moreover, the as-prepared CuInS2 nanocrystals were assembled as a simple prototype thin-film solar cell (Au/CuInS2 nanocrystals/TiO2 nanorod arrays/FTO) by a facile drop-casting method. The obtained thin-film solar cells reached an overall conversion efficiency of 0.21% under AM1.5 (100 mW cm-2) illumination by optimizing the experimental conditions, indicating that the nanocrystals had potential application in thin film solar cells with low cost.(4) A novel solar cell was explored. Two thin films (CuInS2/FTO and CuInS2/TiO2/FTO) were deposited by a facile solvothermal method. The results showed that the CuInS2 films deposited on the FTO conductive glass substrates were composed of nanoplates and microspheres. The thickness of the CuInS2/FTO films can be adjusted from 1-8μm by controlling the solution concentration of the reactants. While, the prepared 10μm thick CuInS2 film on the TiO2 film substrate consisted of nanoplates. The UV-vis absorption spectra revealed that the CuInS2 thin films had a strong absorption around 400-850 nm and the band-gap energy was tunable in the range of 1.45-1.61 eV with the variation of Cu/In ratio from 1.20 to 0.90. Furthermore, two types of thin film solar cells, which possessed separately the top-down composition of Ag/CdS/CuInS2/FTO and Au/CuInS2/TiO2/FTO were fabricated after heat-treatment. Under AM 1.5 irradiation (100mW cm-2), the conversion efficiencies of the as-prepared Ag/CdS/CuInS2/FTO and Au/CuInS2/TiO2/FTO were 0.33% and 0.29%, respectively.

Related Dissertations

  1. Under microaerobic conditions closed calcium carbide furnace exhaust COS gas adsorption purification,X781
  2. Investigation of Preparation and Properties of Ordered Porous TiO2,TB383.2
  3. Recovery Sulphur from Zinc Concentrate of Pressure Acid Leaching Residue,X751
  4. Pyridine Metal Complexes electronic spectra and redox properties of theoretical research,O627
  5. Synthesis of Macrocyclic Coordination Compound and Oxidation of Sulfides,O621.25
  6. Development of Timing Sync Circuit of Photo-cathode Rf Gun and Research on Application Possibility of Radically Polarized Laser,TL503.3
  7. Synthesis and Characterization of Metal Complexes Supported by S/N Ligands and Their Optical and Electrical Properties,O641.4
  8. The Synthesis of Structural Controllable Titanium Dioxide Nanorods Array and Its Electrochemical Performance,TB383.2
  9. The Biological Inhibition to SRB and Its Electrochemical Evaluation,X172
  10. Colorimetric Determination of CdS Nanocrystals Concentration,TB383.1
  11. Dssc Light Anode Preparation and Performance Study,TM914.4
  12. Preparation of Titanium Nanocrystals from Titanium (Ⅳ) Bis (Ammonium Lactato) Dihydroxide and Their Application in DSSCs,TB383.1
  13. Studies on Itraconzole Nanocrystal Dry Suspension,TQ463.53
  14. The Research of the Dye-Sensitized Nanocrystalline TiO2 Solar Cells,TM914.4
  15. Raman Investigation of Silicon Nanocrystals: Quantum Confinement and Laser-induced Thermal Effects,TB383.2
  16. Cu 2 ZnSnS x Se 4-x thin film solar cell absorber material Preparation and Characterization,TM914.4
  17. Electrochemical anodic oxidation of sulfide,X703
  18. TiO 2 nanocrystalline porous anodic film synthesis and optical properties of the photoelectric conversion,TM914.4
  19. Wide spectrum monitor thin films by electron beam evaporation system development and application,O484.1
  20. Silicon nanocrystal photoluminescence and electroluminescence modulation studies,TB383.1
  21. Preparation and Properties of BN, GaN, ZnS Nanomaterials,TB383.1

CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Photocell > Solar cells
© 2012 www.DissertationTopic.Net  Mobile